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Network Working Group                                         J. Reschke
Internet-Draft                                                greenbytes
Expires: August 17, 2005                               February 13, 2005


                       The HTTP ADDMEMBER Method
                    draft-reschke-http-addmember-00

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of Section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
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   RFC 3668.

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   This Internet-Draft will expire on August 17, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   Frequently, servers may want to allow resource creation through HTTP,
   but are not able to support HTTP's PUT method for creating new
   resources, as resource names are completely controlled by the server.
   This document proposes a new HTTP method called "ADDMEMBER" with
   semantics similar to those of PUT, except for the fact that the
   server chooses the URI for the newly created resource.




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Editorial Note

   Distribution of this document is unlimited.  Please send comments to
   the Hypertext Transfer Protocol (HTTP) mailing list at
   ietf-http-wg@w3.org [1], which may be joined by sending a message
   with subject "subscribe" to ietf-http-wg-request@w3.org [2].

   Discussions of the HTTP working group are archived at
   <http://lists.w3.org/Archives/Public/ietf-http-wg/>.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Notational Conventions . . . . . . . . . . . . . . . . . . . .  3
   3.  ADDMEMBER method . . . . . . . . . . . . . . . . . . . . . . .  3
     3.1   Example: ADDMEMBER . . . . . . . . . . . . . . . . . . . .  4
   4.  Feature Discovery  . . . . . . . . . . . . . . . . . . . . . .  4
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  4
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  4
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     7.1   Normative References . . . . . . . . . . . . . . . . . . .  4
     7.2   Informative References . . . . . . . . . . . . . . . . . .  5
       Author's Address . . . . . . . . . . . . . . . . . . . . . . .  5
   A.  Dicussion of alternative approaches  . . . . . . . . . . . . .  5
     A.1   POST . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     A.2   Implicit PUT extensions  . . . . . . . . . . . . . . . . .  5
     A.3   Explicit extensions based on RFC2774 . . . . . . . . . . .  6
       Intellectual Property and Copyright Statements . . . . . . . .  7























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1.  Introduction

   Frequently, servers may want to allow resource creation through HTTP,
   but are not able to support HTTP's PUT method for creating new
   resources, as resource names are completely controlled by the server
   (see [RFC2616], Section 9.6).  This document proposes a new HTTP
   method called "ADDMEMBER" with semantics similar to those of PUT,
   except for the fact that the server chooses the URI for the newly
   created resource.

   Some alternative approaches are summarized in Appendix A for
   discussion.

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   All terminology not defined explicitly in this document is inherited
   from [RFC2616].

3.  ADDMEMBER method

   The ADDMEMBER method requests that the enclosed entity be stored as a
   new resource under a URI selected by the server based on the Request-
   URI referring to a container resource. [[anchor4: Do we need to
   require a specific containment model here, such as WebDAV's
   collections? --reschke]]

   If a new resource is created, the origin server MUST inform the user
   agent via the 201 (Created) response, including a "Location" response
   header containing the URI of the newly created resource.  If the
   resource could not be created, an appropriate error response SHOULD
   be given that reflects the nature of the problem.  The recipient of
   the entity MUST NOT ignore any Content-* (e.g.  Content-Range)
   headers that it does not understand or implement and MUST return a
   501 (Not Implemented) response in such cases.

   Responses to this method are not cacheable.

   The fundamental difference between the ADDMEMBER and PUT requests is
   reflected in the different meaning of the Request-URI.  The URI in an
   ADDMEMBER request identifies the resource that will handle the
   enclosed entity by storing it as a new resource with a server-
   selected URI.  In contrast, the URI in a PUT request identifies the
   entity enclosed with the request -- the user agent knows what URI is
   intended and the server MUST NOT attempt to apply the request to some



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   other resource.

   ADDMEMBER requests MUST obey the message transmission requirements
   set out in Section 8.2 of [RFC2616].

   Entity-headers in the ADDMEMBER request SHOULD be handled the same
   way as defined for PUT.

   This method is neither safe nor idempotent (see [RFC2616], Section
   9).

3.1  Example: ADDMEMBER

   >> Request:

   ADDMEMBER /CollY HTTP/1.1
   Host: www.example.com
   Content-Type: application/xml

   <foobar/>

   >> Response:

   HTTP/1.1 201 Created
   Location: http://www.example.com/CollY/3253623


4.  Feature Discovery

   Clients can detect server support for the ADDMEMBER method by
   inspecting the "Allow" response header returned for an OPTIONS
   request on the Request-URI.  Note that a server may support ADDMEMBER
   only on a subset of the URIs it is handling.

5.  Security Considerations

   The same security considerations as those for HTTP PUT apply.

6.  Acknowledgements

   [[anchor7: TBD. --reschke]]

7.  References

7.1  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.



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   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

7.2  Informative References

   [RFC2774]  Nielsen, H., Leach, P., and S. Lawrence, "An HTTP
              Extension Framework", RFC 2774, February 2000.

URIs

   [1]  <mailto:ietf-http-wg@w3.org>

   [2]  <mailto:ietf-http-wg-request@w3.org?subject=subscribe>


Author's Address

   Julian F. Reschke
   greenbytes GmbH
   Salzmannstrasse 152
   Muenster, NW  48159
   Germany

   Phone: +49 251 2807760
   Fax:   +49 251 2807761
   Email: julian.reschke@greenbytes.de
   URI:   http://greenbytes.de/tech/webdav/

Appendix A.  Dicussion of alternative approaches

   This section tries to summarize alternative approaches.

A.1  POST

   POST is a very generic method and therefore can be used to achieve
   the same result.  However, clients that rely on the very specific
   processing defined for ADDMEMBER would need a reliable way to
   discover how the server is processing POST requests, requiring a new
   discovery mechanism.

A.2  Implicit PUT extensions

   Several communities are discussing to simply use PUT in these
   situations.  The server would allocate a new URI and send a
   "Location" response header with the new URI, rather than storing the
   entity at the Request-URI.  This seems to be contrary to the stated
   HTTP semantics for PUT, but would allow existing clients to make use



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   of this functionality (although it's not clear how well they would
   handle the "URI change upon creation" scenario.

   Example:

   >> Request:

   PUT /CollY/something HTTP/1.1
   Host: www.example.com
   If-None-Match: *
   Content-Type: application/xml

   <foobar/>

   >> Response:

   HTTP/1.1 201 Created
   Location: http://www.example.com/CollY/3253623


A.3  Explicit extensions based on RFC2774

   The extension mechanism defined in [RFC2774] could be used to extend
   either POST or PUT with the desired semantics.

   Example:

   >> Request:

   M-POST /CollY HTTP/1.1
   Host: www.example.com
   Man: "urn:ietf:id:draft-reschke-http-addmember-00"; ns=00
   00-store-enclosed-entity:
   Content-Type: application/xml

   <foobar/>

   >> Response:

   HTTP/1.1 201 Created
   Location: http://www.example.com/CollY/3253623










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   Copyright (C) The Internet Society (2005).  This document is subject
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Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




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